iDefense is best known for its controversial vulnerability contributor program, which rewards hackers for advance notification of unpublished vulnerabilities or exploit code. It's not immediately clear if the program will continue post acquisition.

VeriSign's rivals in the managed security market include Symantec and Cybertrust, both of which came into the market niche through acquisitions, and Counterpane. In a statement, VeriSign said revenue and earnings contribution from the acquisition wouldn't affect its financial results in 2005. ®